package BC129_小乐乐计算函数;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();

        double m = (max3(a + b, b, c)) / (max3(a, b + c, c) + max3(a, b, b + c));
        System.out.printf("%.2f", m);
    }

    private static double max3(int a, int b, int c) {
        int max1 = a > b ? a : b;
        int max = max1 > c ? max1 : b;
        return max;
    }
}
